About 400 people, dressed for a gala, will take their seats Friday evening in what once was a dilapidated Frankford Avenue movie house. Three women in nun’s habits will pop up, administering parochial-school demands: Get rid of the gum! Flip off those cell phones!

The lights will dim, the loopy musical Nunsense will begin – and Northeast Philadelphia will have its first professional live-performance theater, in an area where many people (those in the Northeast included) may not expect to find one.

The opening of the sparkling Devon Theater is an example both of neighborhood tenacity and of a professional Philadelphia theater community whose growth – against the economic odds – seems unstoppable.

“I welcome them to the theater community,” says Margie Salvante, executive director of the Theatre Alliance of Greater Philadelphia. “The theater industry, on a national level, is really focused on Philadelphia as a hot spot right now.”

Excitement has been building in the Mayfair neighborhood where the Devon, on Frankford between Barnett and Stirling Streets, heralds a new level of local entertainment and the gradual revitalization that has taken hold. A call for volunteers to help usher, greet, and take on other duties drew more than 200 responses.

“I’ve seen the Devon at its worst. I want to see the theater now that it’s alive again,” says one of those volunteers, 76-year-old Kathleen Murray, who sometimes goes to the Arden Theatre in Old City or Glenside’s Keswick but relishes the idea of being able to see a show closer to home.

Her orientation was last weekend. “Will I be selling popcorn? Anything!” she says.

Whatever Murray does, she’ll be doing it in a state-of-the-art theater with a new 40-foot stage, and cupholders at each seat – just like at the movies. Its sound design boasts under-the-stage speakers to balance music for the front rows, and necklace transmitters that beam sound directly to the hearing aids of ticketholders who need them.

It even has a skybox of sorts, a roomy 20-seat balcony level for VIPs or rentals, with its own restrooms and catering space.

A local company, Fuse Management, which produces theatrical and special events nationwide (including on the Parkway and at Penn’s Landing), has been in charge of renovation and will mount the productions. Fuse opens the Devon with an agreement with Actors’ Equity, the professional union of theater artists – not generally the case with nascent theater companies. (The nearest theater – Kensington’s Walking Fish, five miles south on Frankford Avenue – pays its actors but is not aligned with Equity.)

“We could actually do it without any unions,” says Stephen McEntee, a Fuse employee instrumental in the Devon’s rescue from termite-riddled, roof-rotting destruction. “But we believe in it because of the talent, and we believe that people should be able to make a living at their profession, the arts or otherwise.”

The Devon, felicitously located near two Mayfair eat-and-drink landmarks – Tony’s Place across the street and Chickie’s & Pete’s to one side – is now owned by Mayfair’s Community Development Corp. (CDC), the neighborhood revitalization group that has a $6 million investment in the theater and the still-to-come surrounding streetscape.

State, federal, city, and private money is funding two-thirds of the project; the rest comes from a loan to the CDC from Beneficial, says Brian Patrick King, its executive director and a Mayfair native.

The theater, he says, will be a production house presenting its own shows, a booking house bringing in others, and a rental on off nights for groups that can use its spaces. The CDC hopes six new retail storefronts on the block, also part of the project, will help pay the Devon’s costs.

The theater even plans to use its own shows to help charities raise money: The charity guarantees the house, then sets fund-raising ticket prices, and the Devon provides all the services, cut-rate.

Like other projects now coming to fruition in a tough economy, the new Devon has roots in a more optimistic time earlier in the decade, when a study showed Mayfair lacked arts and culture in general.

At that time, on the Frankford Avenue corridor that mixed long-standing businesses with newer ones opened by young owners, the Devon was the last old-time movie venue standing, if barely. So five years ago the CDC, looking to create an arts scene – and the nighttime buzz, dining, and shopping that often come with it – bought the Devon for $800,000.

The theater, built in 1946, was among the city’s last single-screen cinemas, eclipsed by the era of multiplexes. In the beginning, its big, twinkly marquee – a landmark re-created and working again – advertised first-run films in what remains a solid, largely Irish Catholic neighborhood (where Nunsense should sell out). But as the business changed, it became a second-run house and then, in the ’70s, declined into porn; neighbors called it “the dirty Devon,” and worse.

One day in 1978, they woke to see a proclamation on the marquee: “No More Sex.” The Devon went back to being a second-run cinema, at 99 cents a ticket until 1985, when (amid some head-shaking) the price went up to $1.

Mike Lally, 29, a Mayfair native and manager of the new Devon, says that when he was a grade schooler, “the last thing I saw here was The Terminator – the original Terminator.”

The theater struggled and shut down, reopened for a few years with classic films in the late ’90s, then closed for good.

“When I walked in, it was like something out of a horror movie,” says Amy Pickering, the new theater’s education director, who will run its summer camp, workshops, and adult programs. That was in early 2008; the building was a dilapidated shell.

She and her husband, Michael – now the Devon’s artistic director – live in Sicklerville, Camden County, and had been traveling the country with a music-comedy dueling-piano show. They came at the behest of Fuse Management, drove around Mayfair, and were intrigued.

Their initial look at the Devon “terrified us a little bit,” Michael says, but they liked the neighborhood. “You could tell there wasn’t a lot of arts access around here, though,” he says, “and we decided it would be great to be part of providing that.”

The Pickerings understand that their shows will draw theatergoers as well as those who have never attended a live performance. To that end, the Devon’s Web site not only lists the usual particulars (ticket prices from $25 to $35, and the like), but also offers guidance on when to applaud.

“People may be a little intimidated,” Michael Pickering says, “and we want this theater to be as accessible as possible to everyone.”

That goes for what’s on offer, too, which returns the Devon to family-theater roots. You want cutting edge? The Devon is not your stage. (The Odd Couple is the just-announced second show.)

Its Web site poses the question: “Is this show appropriate for my kids?” The answer: “At the Devon Theater, we do not produce shows that are ‘for adults only.’ ”

Says Michael Pickering: “It’s a family area. We never want to put a show up with a parental advisory.”